That Full Parry wasn't "hard" on the match up bases, because Daigo was waiting for Justin to pull off SAII and alot of the best 3S players can parry that in their sleep anyhow. The reason it was so hyped was mainly due to the fact that it was done during the Final Four.
However, Justin Wong vs Yipes in their MvC2 was by far the greatest moment in Evolution History. That is 100x more ridiculous then Daigo's Parry, because it was a single character Cyclops against a nearly full health Top-Tier Team of Magneto/Storm/Psylocke Team. If you watch the match more closely, he does crazy things like Psycho Shoryuken's with Cyclops that hits perfectly! If he missed one of those, Mag's can easily Rom or Reset Cyclops to oblivion in less then 5 seconds.
However Justin Wong was absolutely amazing in there, and was able to get the win with Cyclops against none other then Yipes, who hands down has the best MSP team on the planet. This is a much, much, much, much greater feat of accomplishment then Daigo's feat with his Full Parry, simply because the fear factor, and danger was nowhere near as high as what Justin had to do in order to win.
However "Best Moment in Fighting Game History" I really don't know, there's so much that we don't see from other fighting games (KoF, Tekken, Virtua Fighter, AH, etc, etc), and not to mention from it's past as well, like OG SFII etc, etc.
I mean, how about B3's Famous Alpha 2 match up of the World's two Best Street Fighter Alpha 2 players of all time Alex Valle (Sagat) vs John Choi (Ken) match up. That one should deserve a seriously huge nod...just watch the video down below.
John Choi (Ken) vs Alex Valle (Sagat) Alpha 2 B3 Tournament
http://www.youtube.com/watch?v=XfZNpXvyk94
Sagat is down to less then 10% life, hell a fierce will kill Valle on the spot, however he baits and lands a CC, then a cross up into c. strong, fp Tiger, and just as John activates CC with Ken to come in for the kill, Valle lands with a psychic Tiger Uppercut for the win. So with less then 10% life (judging by the video it's even less then that!) he depletes over 60% of Choi's Ken to win it all to place 1st and become Champion within the final last round, nothing short but spectacular.
However, there's so much more and to me it's too hard to simply rank "the best" for one.